Extracting prog: 1m12.408167916s
Minimizing prog: 3m26.285305472s
Simplifying prog options: 0s
Extracting C: 32.07918904s
Simplifying C: 6m12.537469625s


extracting reproducer from 1 programs
testing a last program of every proc
single: executing 1 programs separately with timeout 30s
testing program (duration=30s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
detailed listing:
executing program 0:
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
r1 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, &(0x7f0000000740)=@pppol2tpv3={0x18, 0x1, {0x3, r1, {0x2, 0x4e23, @broadcast}, 0x2, 0x0, 0x4}}, 0x2e)
ioctl$BTRFS_IOC_INO_LOOKUP_USER(r0, 0xd000943e, 0x0)

program crashed: KASAN: use-after-free Write in pppol2tp_release
single: successfully extracted reproducer
found reproducer with 4 syscalls
minimizing guilty program
testing program (duration=32.563836099s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp
detailed listing:
executing program 0:
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
r1 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, &(0x7f0000000740)=@pppol2tpv3={0x18, 0x1, {0x3, r1, {0x2, 0x4e23, @broadcast}, 0x2, 0x0, 0x4}}, 0x2e)

program did not crash
testing program (duration=32.563836099s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
detailed listing:
executing program 0:
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
socket$inet6_udp(0xa, 0x2, 0x0)
ioctl$BTRFS_IOC_INO_LOOKUP_USER(r0, 0xd000943e, 0x0)

program did not crash
testing program (duration=32.563836099s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
detailed listing:
executing program 0:
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
connect$pppl2tp(r0, &(0x7f0000000740)=@pppol2tpv3={0x18, 0x1, {0x3, 0xffffffffffffffff, {0x2, 0x4e23, @broadcast}, 0x2, 0x0, 0x4}}, 0x2e)
ioctl$BTRFS_IOC_INO_LOOKUP_USER(r0, 0xd000943e, 0x0)

program did not crash
testing program (duration=32.563836099s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
detailed listing:
executing program 0:
r0 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(0xffffffffffffffff, &(0x7f0000000740)=@pppol2tpv3={0x18, 0x1, {0x3, r0, {0x2, 0x4e23, @broadcast}, 0x2, 0x0, 0x4}}, 0x2e)
ioctl$BTRFS_IOC_INO_LOOKUP_USER(0xffffffffffffffff, 0xd000943e, 0x0)

program did not crash
testing program (duration=32.563836099s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
detailed listing:
executing program 0:
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, 0x0, 0x0)
ioctl$BTRFS_IOC_INO_LOOKUP_USER(r0, 0xd000943e, 0x0)

program did not crash
extracting C reproducer
testing compiled C program (duration=32.563836099s, {Threaded:true Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
program crashed: KASAN: use-after-free Write in pppol2tp_release
simplifying C reproducer
testing compiled C program (duration=32.563836099s, {Threaded:false Repeat:true RepeatTimes:0 Procs:5 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
program crashed: KASAN: use-after-free Write in pppol2tp_release
testing compiled C program (duration=32.563836099s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:false Cgroups:false BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
program crashed: KASAN: use-after-free Write in pppol2tp_release
testing compiled C program (duration=32.563836099s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:false UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
program crashed: KASAN: use-after-free Read in pppol2tp_sock_to_session
a never seen crash title: KASAN: use-after-free Read in pppol2tp_sock_to_session, ignore
testing compiled C program (duration=32.563836099s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:true NetReset:false Cgroups:false BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
program crashed: KASAN: use-after-free Write in pppol2tp_release
testing compiled C program (duration=32.563836099s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
program crashed: KASAN: use-after-free Write in pppol2tp_release
testing compiled C program (duration=32.563836099s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
program crashed: KASAN: use-after-free Write in pppol2tp_release
testing compiled C program (duration=32.563836099s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
program crashed: KASAN: use-after-free Read in pppol2tp_sock_to_session
a never seen crash title: KASAN: use-after-free Read in pppol2tp_sock_to_session, ignore
testing compiled C program (duration=32.563836099s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
program crashed: KASAN: use-after-free Write in pppol2tp_release
testing compiled C program (duration=32.563836099s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:false HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
program crashed: KASAN: use-after-free Write in pppol2tp_release
testing compiled C program (duration=32.563836099s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:true UseTmpDir:false HandleSegv:false Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
program crashed: KASAN: use-after-free Write in pppol2tp_release
testing compiled C program (duration=32.563836099s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:false Swap:true UseTmpDir:false HandleSegv:false Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
program crashed: KASAN: use-after-free Write in pppol2tp_release
testing compiled C program (duration=32.563836099s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:false Swap:false UseTmpDir:false HandleSegv:false Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
program crashed: KASAN: use-after-free Write in pppol2tp_release
testing program (duration=32.563836099s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:false Swap:false UseTmpDir:false HandleSegv:false Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
detailed listing:
executing program 0:
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
r1 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, &(0x7f0000000740)=@pppol2tpv3={0x18, 0x1, {0x3, r1, {0x2, 0x4e23, @broadcast}, 0x2, 0x0, 0x4}}, 0x2e)
ioctl$BTRFS_IOC_INO_LOOKUP_USER(r0, 0xd000943e, 0x0)

program crashed: KASAN: use-after-free Read in rcu_cblist_dequeue
validation run: crashed=true
testing program (duration=32.563836099s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:false Swap:false UseTmpDir:false HandleSegv:false Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
detailed listing:
executing program 0:
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
r1 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, &(0x7f0000000740)=@pppol2tpv3={0x18, 0x1, {0x3, r1, {0x2, 0x4e23, @broadcast}, 0x2, 0x0, 0x4}}, 0x2e)
ioctl$BTRFS_IOC_INO_LOOKUP_USER(r0, 0xd000943e, 0x0)

program crashed: KASAN: use-after-free Write in pppol2tp_release
validation run: crashed=true
testing program (duration=32.563836099s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:false Swap:false UseTmpDir:false HandleSegv:false Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): socket$pppl2tp-socket$inet6_udp-connect$pppl2tp-ioctl$BTRFS_IOC_INO_LOOKUP_USER
detailed listing:
executing program 0:
r0 = socket$pppl2tp(0x18, 0x1, 0x1)
r1 = socket$inet6_udp(0xa, 0x2, 0x0)
connect$pppl2tp(r0, &(0x7f0000000740)=@pppol2tpv3={0x18, 0x1, {0x3, r1, {0x2, 0x4e23, @broadcast}, 0x2, 0x0, 0x4}}, 0x2e)
ioctl$BTRFS_IOC_INO_LOOKUP_USER(r0, 0xd000943e, 0x0)

program crashed: KASAN: use-after-free Read in rcu_cblist_dequeue
validation run: crashed=true
reproducing took 13m15.42592197s
repro crashed as (corrupted=false):
==================================================================
BUG: KASAN: use-after-free in rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
Read of size 8 at addr ffff88810ea2f990 by task kworker/0:2/331

CPU: 0 PID: 331 Comm: kworker/0:2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
 <IRQ>
 __dump_stack+0x21/0x24 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_address_description+0x71/0x200 mm/kasan/report.c:316
 print_report+0x4a/0x60 mm/kasan/report.c:420
 kasan_report+0x122/0x150 mm/kasan/report.c:524
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:351
 rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
 rcu_do_batch+0x4bc/0xc30 kernel/rcu/tree.c:2285
 rcu_core+0x486/0xf00 kernel/rcu/tree.c:2557
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2574
 handle_softirqs+0x1d7/0x600 kernel/softirq.c:642
 __do_softirq+0xb/0xd kernel/softirq.c:680
 do_softirq+0xdc/0x130 kernel/softirq.c:524
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x75/0x80 kernel/softirq.c:448
 __raw_write_unlock_bh include/linux/rwlock_api_smp.h:281 [inline]
 _raw_write_unlock_bh+0x2f/0x50 kernel/locking/spinlock.c:366
 addrconf_dad_work+0x928/0x14a0 net/ipv6/addrconf.c:4241
 process_one_work+0x717/0xc30 kernel/workqueue.c:2302
 worker_thread+0xa4d/0x11d0 kernel/workqueue.c:2449
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Allocated by task 372:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_alloc_info+0x1f/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:380 [inline]
 __kasan_kmalloc+0x95/0xb0 mm/kasan/common.c:389
 kasan_kmalloc include/linux/kasan.h:212 [inline]
 __do_kmalloc_node mm/slab_common.c:938 [inline]
 __kmalloc+0xb4/0x1e0 mm/slab_common.c:951
 kmalloc include/linux/slab.h:568 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 l2tp_session_create+0x38/0xbd0 net/l2tp/l2tp_core.c:1609
 pppol2tp_connect+0xbf5/0x1640 net/l2tp/l2tp_ppp.c:771
 __sys_connect_file net/socket.c:2000 [inline]
 __sys_connect+0x3da/0x460 net/socket.c:2017
 __do_sys_connect net/socket.c:2027 [inline]
 __se_sys_connect net/socket.c:2024 [inline]
 __x64_sys_connect+0x7a/0x90 net/socket.c:2024
 x64_sys_call+0x88d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:43
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 312:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x132/0x180 mm/kasan/common.c:242
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:250
 kasan_slab_free include/linux/kasan.h:178 [inline]
 slab_free_hook mm/slub.c:1750 [inline]
 slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1776
 slab_free mm/slub.c:3712 [inline]
 __kmem_cache_free+0xb7/0x1b0 mm/slub.c:3728
 kfree+0x6f/0xf0 mm/slab_common.c:990
 l2tp_session_free net/l2tp/l2tp_core.c:168 [inline]
 l2tp_session_put+0xaf/0x1a0 net/l2tp/l2tp_core.c:193
 l2tp_session_delete+0x3df/0x4d0 net/l2tp/l2tp_core.c:1582
 l2tp_tunnel_closeall net/l2tp/l2tp_core.c:1228 [inline]
 l2tp_tunnel_del_work+0x199/0x410 net/l2tp/l2tp_core.c:1266
 process_one_work+0x717/0xc30 kernel/workqueue.c:2302
 worker_thread+0xa4d/0x11d0 kernel/workqueue.c:2449
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Last potentially related work creation:
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xb6/0xc0 mm/kasan/generic.c:486
 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:496
 __call_rcu_common kernel/rcu/tree.c:2807 [inline]
 call_rcu+0xcf/0xf50 kernel/rcu/tree.c:2926
 pppol2tp_release+0x1e3/0x2b0 net/l2tp/l2tp_ppp.c:446
 __sock_release net/socket.c:652 [inline]
 sock_close+0xc9/0x220 net/socket.c:1389
 __fput+0x1fd/0x8f0 fs/file_table.c:320
 ____fput+0x15/0x20 fs/file_table.c:348
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0x9b/0xb0 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Second to last potentially related work creation:
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xb6/0xc0 mm/kasan/generic.c:486
 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:496
 kvfree_call_rcu+0x8b/0x7a0 kernel/rcu/tree.c:3445
 net_assign_generic net/core/net_namespace.c:117 [inline]
 ops_init+0x26f/0x470 net/core/net_namespace.c:132
 __register_pernet_operations net/core/net_namespace.c:1165 [inline]
 register_pernet_operations+0x2a0/0x600 net/core/net_namespace.c:1238
 register_pernet_subsys+0x28/0x40 net/core/net_namespace.c:1279
 ipsec_pfkey_init+0x3c/0xac net/key/af_key.c:3915
 do_one_initcall+0x1d6/0x580 init/main.c:1433
 do_initcall_level+0x174/0x2df init/main.c:1506
 do_initcalls+0x50/0x92 init/main.c:1522
 do_basic_setup+0x92/0x99 init/main.c:1541
 kernel_init_freeable+0x2d1/0x42d init/main.c:1761
 kernel_init+0x1d/0x1c0 init/main.c:1649
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff88810ea2f800
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
 512-byte region [ffff88810ea2f800, ffff88810ea2fa00)

The buggy address belongs to the physical page:
page:ffffea00043a8b00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10ea2c
head:ffffea00043a8b00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 0000000000000000 dead000000000001 ffff888100042f00
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 3473375891, free_ts 3473193845
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2672
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2679
 get_page_from_freelist+0x2ca9/0x2d20 mm/page_alloc.c:4586
 __alloc_pages+0x1fa/0x610 mm/page_alloc.c:5930
 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
 allocate_slab mm/slub.c:1967 [inline]
 new_slab+0x98/0x3e0 mm/slub.c:2020
 ___slab_alloc+0x70f/0xb70 mm/slub.c:3177
 __slab_alloc+0x5e/0xa0 mm/slub.c:3263
 slab_alloc_node mm/slub.c:3348 [inline]
 __kmem_cache_alloc_node+0x204/0x2d0 mm/slub.c:3423
 __do_kmalloc_node mm/slab_common.c:937 [inline]
 __kmalloc_node_track_caller+0xa1/0x1e0 mm/slab_common.c:958
 kmalloc_reserve net/core/skbuff.c:449 [inline]
 __alloc_skb+0x226/0x4a0 net/core/skbuff.c:518
 alloc_skb include/linux/skbuff.h:1322 [inline]
 nlmsg_new include/net/netlink.h:987 [inline]
 inet_netconf_notify_devconf+0x169/0x220 net/ipv4/devinet.c:2128
 __devinet_sysctl_register+0x2af/0x320 net/ipv4/devinet.c:2618
 devinet_sysctl_register+0x169/0x1e0 net/ipv4/devinet.c:2652
 inetdev_init+0x2ca/0x510 net/ipv4/devinet.c:280
 inetdev_event+0x1f4/0x10a0 net/ipv4/devinet.c:1547
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1580 [inline]
 free_pcp_prepare mm/page_alloc.c:1654 [inline]
 free_unref_page_prepare+0x80c/0x820 mm/page_alloc.c:3621
 free_unref_page+0x93/0x530 mm/page_alloc.c:3719
 free_the_page mm/page_alloc.c:863 [inline]
 __free_pages+0x67/0x100 mm/page_alloc.c:6020
 free_pages+0x82/0x90 mm/page_alloc.c:6031
 __stack_depot_save+0x45f/0x490 lib/stackdepot.c:506
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_set_track+0x60/0x70 mm/kasan/common.c:53
 kasan_save_alloc_info+0x1f/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:380 [inline]
 __kasan_kmalloc+0x95/0xb0 mm/kasan/common.c:389
 kasan_kmalloc include/linux/kasan.h:212 [inline]
 kmalloc_trace+0x40/0xb0 mm/slab_common.c:1033
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 ref_tracker_alloc+0x16b/0x4a0 lib/ref_tracker.c:85
 __netdev_tracker_alloc include/linux/netdevice.h:4085 [inline]
 netdev_hold include/linux/netdevice.h:4114 [inline]
 netdev_queue_add_kobject net/core/net-sysfs.c:1657 [inline]
 netdev_queue_update_kobjects+0x181/0x470 net/core/net-sysfs.c:1712
 register_queue_kobjects net/core/net-sysfs.c:1773 [inline]
 netdev_register_kobject+0x281/0x330 net/core/net-sysfs.c:2013
 register_netdevice+0xec9/0x1550 net/core/dev.c:10206
 register_netdev+0x3e/0x50 net/core/dev.c:10332
 sit_init_net+0x243/0x4e0 net/ipv6/sit.c:1861
 ops_init+0x2ce/0x470 net/core/net_namespace.c:138

Memory state around the buggy address:
 ffff88810ea2f880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88810ea2f900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88810ea2f980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff88810ea2fa00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 

final repro crashed as (corrupted=false):
==================================================================
BUG: KASAN: use-after-free in rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
Read of size 8 at addr ffff88810ea2f990 by task kworker/0:2/331

CPU: 0 PID: 331 Comm: kworker/0:2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
 <IRQ>
 __dump_stack+0x21/0x24 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_address_description+0x71/0x200 mm/kasan/report.c:316
 print_report+0x4a/0x60 mm/kasan/report.c:420
 kasan_report+0x122/0x150 mm/kasan/report.c:524
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:351
 rcu_cblist_dequeue+0x6c/0xb0 kernel/rcu/rcu_segcblist.c:75
 rcu_do_batch+0x4bc/0xc30 kernel/rcu/tree.c:2285
 rcu_core+0x486/0xf00 kernel/rcu/tree.c:2557
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2574
 handle_softirqs+0x1d7/0x600 kernel/softirq.c:642
 __do_softirq+0xb/0xd kernel/softirq.c:680
 do_softirq+0xdc/0x130 kernel/softirq.c:524
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x75/0x80 kernel/softirq.c:448
 __raw_write_unlock_bh include/linux/rwlock_api_smp.h:281 [inline]
 _raw_write_unlock_bh+0x2f/0x50 kernel/locking/spinlock.c:366
 addrconf_dad_work+0x928/0x14a0 net/ipv6/addrconf.c:4241
 process_one_work+0x717/0xc30 kernel/workqueue.c:2302
 worker_thread+0xa4d/0x11d0 kernel/workqueue.c:2449
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Allocated by task 372:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_alloc_info+0x1f/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:380 [inline]
 __kasan_kmalloc+0x95/0xb0 mm/kasan/common.c:389
 kasan_kmalloc include/linux/kasan.h:212 [inline]
 __do_kmalloc_node mm/slab_common.c:938 [inline]
 __kmalloc+0xb4/0x1e0 mm/slab_common.c:951
 kmalloc include/linux/slab.h:568 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 l2tp_session_create+0x38/0xbd0 net/l2tp/l2tp_core.c:1609
 pppol2tp_connect+0xbf5/0x1640 net/l2tp/l2tp_ppp.c:771
 __sys_connect_file net/socket.c:2000 [inline]
 __sys_connect+0x3da/0x460 net/socket.c:2017
 __do_sys_connect net/socket.c:2027 [inline]
 __se_sys_connect net/socket.c:2024 [inline]
 __x64_sys_connect+0x7a/0x90 net/socket.c:2024
 x64_sys_call+0x88d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:43
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 312:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x132/0x180 mm/kasan/common.c:242
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:250
 kasan_slab_free include/linux/kasan.h:178 [inline]
 slab_free_hook mm/slub.c:1750 [inline]
 slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1776
 slab_free mm/slub.c:3712 [inline]
 __kmem_cache_free+0xb7/0x1b0 mm/slub.c:3728
 kfree+0x6f/0xf0 mm/slab_common.c:990
 l2tp_session_free net/l2tp/l2tp_core.c:168 [inline]
 l2tp_session_put+0xaf/0x1a0 net/l2tp/l2tp_core.c:193
 l2tp_session_delete+0x3df/0x4d0 net/l2tp/l2tp_core.c:1582
 l2tp_tunnel_closeall net/l2tp/l2tp_core.c:1228 [inline]
 l2tp_tunnel_del_work+0x199/0x410 net/l2tp/l2tp_core.c:1266
 process_one_work+0x717/0xc30 kernel/workqueue.c:2302
 worker_thread+0xa4d/0x11d0 kernel/workqueue.c:2449
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Last potentially related work creation:
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xb6/0xc0 mm/kasan/generic.c:486
 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:496
 __call_rcu_common kernel/rcu/tree.c:2807 [inline]
 call_rcu+0xcf/0xf50 kernel/rcu/tree.c:2926
 pppol2tp_release+0x1e3/0x2b0 net/l2tp/l2tp_ppp.c:446
 __sock_release net/socket.c:652 [inline]
 sock_close+0xc9/0x220 net/socket.c:1389
 __fput+0x1fd/0x8f0 fs/file_table.c:320
 ____fput+0x15/0x20 fs/file_table.c:348
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0x9b/0xb0 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Second to last potentially related work creation:
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xb6/0xc0 mm/kasan/generic.c:486
 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:496
 kvfree_call_rcu+0x8b/0x7a0 kernel/rcu/tree.c:3445
 net_assign_generic net/core/net_namespace.c:117 [inline]
 ops_init+0x26f/0x470 net/core/net_namespace.c:132
 __register_pernet_operations net/core/net_namespace.c:1165 [inline]
 register_pernet_operations+0x2a0/0x600 net/core/net_namespace.c:1238
 register_pernet_subsys+0x28/0x40 net/core/net_namespace.c:1279
 ipsec_pfkey_init+0x3c/0xac net/key/af_key.c:3915
 do_one_initcall+0x1d6/0x580 init/main.c:1433
 do_initcall_level+0x174/0x2df init/main.c:1506
 do_initcalls+0x50/0x92 init/main.c:1522
 do_basic_setup+0x92/0x99 init/main.c:1541
 kernel_init_freeable+0x2d1/0x42d init/main.c:1761
 kernel_init+0x1d/0x1c0 init/main.c:1649
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff88810ea2f800
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 400 bytes inside of
 512-byte region [ffff88810ea2f800, ffff88810ea2fa00)

The buggy address belongs to the physical page:
page:ffffea00043a8b00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10ea2c
head:ffffea00043a8b00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 0000000000000000 dead000000000001 ffff888100042f00
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 3473375891, free_ts 3473193845
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2672
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2679
 get_page_from_freelist+0x2ca9/0x2d20 mm/page_alloc.c:4586
 __alloc_pages+0x1fa/0x610 mm/page_alloc.c:5930
 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
 allocate_slab mm/slub.c:1967 [inline]
 new_slab+0x98/0x3e0 mm/slub.c:2020
 ___slab_alloc+0x70f/0xb70 mm/slub.c:3177
 __slab_alloc+0x5e/0xa0 mm/slub.c:3263
 slab_alloc_node mm/slub.c:3348 [inline]
 __kmem_cache_alloc_node+0x204/0x2d0 mm/slub.c:3423
 __do_kmalloc_node mm/slab_common.c:937 [inline]
 __kmalloc_node_track_caller+0xa1/0x1e0 mm/slab_common.c:958
 kmalloc_reserve net/core/skbuff.c:449 [inline]
 __alloc_skb+0x226/0x4a0 net/core/skbuff.c:518
 alloc_skb include/linux/skbuff.h:1322 [inline]
 nlmsg_new include/net/netlink.h:987 [inline]
 inet_netconf_notify_devconf+0x169/0x220 net/ipv4/devinet.c:2128
 __devinet_sysctl_register+0x2af/0x320 net/ipv4/devinet.c:2618
 devinet_sysctl_register+0x169/0x1e0 net/ipv4/devinet.c:2652
 inetdev_init+0x2ca/0x510 net/ipv4/devinet.c:280
 inetdev_event+0x1f4/0x10a0 net/ipv4/devinet.c:1547
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1580 [inline]
 free_pcp_prepare mm/page_alloc.c:1654 [inline]
 free_unref_page_prepare+0x80c/0x820 mm/page_alloc.c:3621
 free_unref_page+0x93/0x530 mm/page_alloc.c:3719
 free_the_page mm/page_alloc.c:863 [inline]
 __free_pages+0x67/0x100 mm/page_alloc.c:6020
 free_pages+0x82/0x90 mm/page_alloc.c:6031
 __stack_depot_save+0x45f/0x490 lib/stackdepot.c:506
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_set_track+0x60/0x70 mm/kasan/common.c:53
 kasan_save_alloc_info+0x1f/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:380 [inline]
 __kasan_kmalloc+0x95/0xb0 mm/kasan/common.c:389
 kasan_kmalloc include/linux/kasan.h:212 [inline]
 kmalloc_trace+0x40/0xb0 mm/slab_common.c:1033
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 ref_tracker_alloc+0x16b/0x4a0 lib/ref_tracker.c:85
 __netdev_tracker_alloc include/linux/netdevice.h:4085 [inline]
 netdev_hold include/linux/netdevice.h:4114 [inline]
 netdev_queue_add_kobject net/core/net-sysfs.c:1657 [inline]
 netdev_queue_update_kobjects+0x181/0x470 net/core/net-sysfs.c:1712
 register_queue_kobjects net/core/net-sysfs.c:1773 [inline]
 netdev_register_kobject+0x281/0x330 net/core/net-sysfs.c:2013
 register_netdevice+0xec9/0x1550 net/core/dev.c:10206
 register_netdev+0x3e/0x50 net/core/dev.c:10332
 sit_init_net+0x243/0x4e0 net/ipv6/sit.c:1861
 ops_init+0x2ce/0x470 net/core/net_namespace.c:138

Memory state around the buggy address:
 ffff88810ea2f880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88810ea2f900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88810ea2f980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff88810ea2fa00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc